2. The length of human pregnancies varies according to a distribution that is approximately normal with mean 266 days and standard deviation 16 days. a) What percent of pregnancies last fewer than 240 days (that is, about 8 months)? b) What percent of pregnancies last between 240 and 270 days (roughly between 8 and 9 months)? c) How long do the longest 20% of pregnancies last? 3. Use software to generate 100 observations from the standard Normal distribution. Make a histogram of these observations. How does the shape of this histogram compare with a Normal density curve? ("Histogram function can be found in the "DATA" tab of the main menu in Excel. Click on Data Analysis" and find "Histogram" in the pop-up menu. If you do not see "Data Analysis" in the "DATA" section, see Appendix for how to install Data Analysis)